‘Tango’ is a mandarin selection developed at Riverside, Calif. from an irradiated bud of the diploid mandarin cultivar ‘W. Murcott’, a mid-late season maturing variety. The pedigree of ‘W. Murcott’ mandarin is unknown but is believed to be a seedling selection from a ‘Murcott’ Tangor tree produced in an open-pollinated field. The cultivar ‘W. Murcott’ from which ‘Tango’ was derived may be identical to a mandarin cultivar known as ‘Afourer’ and also as ‘Nadorcott’. The name ‘W. Murcott’ was assigned to a mandarin cultivar which was imported into the United States as buds in 1985 from Morocco. ‘Afourer’ and ‘Nadorcott’ are known to have originated in Morocco. ‘Nadorcott’ was patented in the United States in 1997 under U.S. Plant Pat. No. 10,480 (filed in January 1997).
‘Tango’ originated as a single plant and was asexually reproduced by grafting of budwood onto rootstocks. ‘Tango’ was selected and propagated as follows. Irradiation of budwood from registered “W. Murcott” trees in Lindcove, Calif. was accomplished in June, 1995 at Riverside using 50 Gray units of gamma irradiation from a Cobalt-60 irradiation source. Buds from this irradiation were propagated onto various rootstocks in the greenhouse at Riverside where they were grown to field-plantable-sized trees. These trees were planted in June 1996 at Riverside. Fruit production and evaluation began in 1998. One tree from this irradiated population (propagated on ‘C32’ citrange rootstock) distinguished itself from the others in having fruit that had very low seed counts with excellent fruit quality and normal fruit production characteristics in comparison to the original ‘W. Murcott’ cultivar. After two seasons of fruiting, this tree (now named ‘Tango’), was selected for further trials in 1999 and in January 2000 buds were taken and propagated onto ‘Carrizo’ and C35 citrange rootstock. Budwood was also sent in April 2000 for evaluation of disease status and elimination of viruses and other pathogens as needed.
Twenty trees were planted at Riverside in June 2001. Fruit production on these 20 trees commenced in 2003. In October 2001 two trees of ‘Tango’, which had been produced from budwood that had been tested and certified as tristeza-free, were sent to Lindcove, Calif. where they were planted in the citrus breeding block. Further propagations from the original selection tree in 2001 were made at Riverside and in June 2002 twenty trees were planted at Irvine, Calif., and 15 trees were planted at Santa Paula, Calif.
Fruit production of these propagated trees (at Lindcove, Irvine and Santa Paula) commenced in 2003 (a few trees at each site) and 2004 (all trees at all sites). In July 2002 budwood was taken from the Lindcove trees and topworked onto a navel orange/‘Carrizo’ citrange tree at Lindcove. In September 2002 eighteen trees, produced from budwood from trees at Lindocove were planted at Arvin, Calif. In August 2003 thirty-six additional trees were propagated at Lindcove from budwood taken from the Lindcove trees and in April 2004, twelve were planted in at Thermal, Calif., and in June 2004, twenty-four trees (twelve at each site) were planted at two sites, Lindcove and Woodlake, Calif. All trials were propagated on ‘Carrizo’ and ‘C35’ citrange rootstocks.